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I have an 03 with 36K miles. Yesterday I was on my way home when I noticed the bike was running cold (165 down from 176). 10 minutes later i was down to 1 cylinder with the second coming on during wide open throttle only. Two blocks from home i could see white smoke (maybe it was blue/white hard to tell with a tinted visor) blowing out the exhaust.

Got home and found the following:
-oil on the front cylinder spark plug
-no oil on the rear cylinder spark plug
-oil seeping from the bottom of the exhaust pipe where the exhaust connects to the head (front cylinder)
-no coolant in the oil
-no oil in the coolant
-oil seeping out of the slip-on pipe
-oil level still between max/min lines

I am planning to do a leak-down test this weekend but would appreciate any other ideas on what could be causing this.

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How was the coolant level?
Your temp will drop when water gets into the cylinder. This doesn't have to be a lot either. Water vapour will also deter ignition. As revs increase, combustion can be achieved due to the water / fuel ratio supporting ignition.
Start the bike up and after 30 seconds touch a damp rag to each of the headers to see which cylinder is not firing. I'm guessing its the front. I would say that what you think is oil may well be a mix of coolant / fuel and carbon. Once the bad one is located you will have some work to do. Hopefully it is coolant and not oil. If it is coolant there are a couple of likely culprits. Head gasket or cylinder liner.
Has your bike been ported?

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Coolant level is between the min and max lines. It has been raining a lot the past week and the RC is my daily so water has gotten everywhere. I don't think it has been ported however I am the third owner (purchased with 6.5k miles).

"Once the bad one is located you will have some work to do." Can you elaborate?

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The front valves never fully close (hooked up an air line to the cylinder via the spark plug) checked the valve clearance and the intake is way off as is one of the exhaust valves. Installing the correct size shims tonight, hopefully that solves it.@Way2Slooow - the coolant at the radiator is full. I think you were spot on with the fuel/carbon mistaken for oil.

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Late last night I installed the new shims (intake clearance was off by .12 and .05mm). Ran a pressure test (intake valves held) and manually turned the crank with no piston/valve contact. Started the bike this morning and after a few minutes of residue burn-off took it for a spin. Two noticeable differences:

-The exhaust note is softer (one exhaust valve was out of spec) / It use to sound like a tractor
-The power band is smoother / before i would hit 5k and the bike would take off similar to a vtec motor, now its a smooth linear power delivery

Fingers crossed i fixed the problem and not just a symptom... next week I have some time to take her out and push it in the canyons to see how she runs.

I appreciate the input way2slooow, if you or anyone else thinks of something else please let me know.

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It may well be that you simply had the valves "riding" a little. Normally this will make the bike hard to start. Once warm they come good. Your symptoms would be an extreme example of this. The smoke is curious. White smoke = water. Gray smoke = oil.
Always keep a record of your valve movements. This will tell you what it happening with your bike. If the same valves close up again you will know there is a deeper issue and can address it.
Hopefully all is well.
May the force be with you.

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Finally a break in the rain and got to take the bike out and push it..... noticeable power loss. Came home checked the front cylinder and its down to 90psi. However at 90psi there is no smoke, of any color, and no miss fire. Question, is it possible i was one tooth off on the intake cam when i was reinstalling it? Or would one tooth off result in piston valve collision? I ask because it is extremely difficult to see the indicator line on the cam to line it up with the head.

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If you are one tooth out you will have a noticable power loss. You could still be ok. If you were to make this mistake toward the danger side you would have felt it bind when you manually turned the engine over. Normally for a gasket to go you will notice a loss of radiator fluid through consumption or from displacement due to combustion pressure entering the cooling system. The fact that both cylinders are now firing is a good sign. Check cam alignment once more. Set the cylinder to top dead center on compression and retest with your air line. Let me know if you are getting any bypass.

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I ran another pressure test (I did it correctly this time) and the pressure is actually 140psi but there is still a power loss. I than ran 20psi of air from the spark plug at TDC and there is no leak from the intake or exhaust but there is an audible air leak from the crank case. I would normally assume that means the piston rings are gone but there is now a loss of coolant in the radiator. Is it possible that its just a head gasket failure or am I seriously looking at a top end rebuild?

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The leak into the case would suggest the ring seal is not all it could be. This leak is not due to a gasket failure. I think I would bite the bullet here and get the job done. Have the valve seats on the head recut and blend them to the ports whilst you're at it. You could spend a lot of money on a full port job but 90% of your gains will come from blending the seats and cleaning up the short turn radius. It will be like a new bike once done.
Alternatively you could just replace the gasket for now and do the rings at a later date.
Good luck.

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Your'e right... Got a quote of $1500 (2k with cylinders) for a top end rebuild. While thats better than i expected its cash I don't have at the moment. The bike is rideable but I don't want to push my luck and make things worse. Fingers crossed i get a decent tax return...

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also, when you did your leakdown test was the engine ice cold? you can't expect a cylinder to seal perfectly when it's cold and hasn't had oil sloshing around recently.

i suspect your healthy cylinder would still let air past the rings when cold. they aren't a perfect seal, simply a seal based on the instantaneous pressure change. you can turn an engine over very slowly with little compression resistance for this reason.

when you say the bike is down on power is it still operating smoothly? is it stumbling at all? there are a lot of things worth checking before deciding it's game over

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@Wibbly The leak down test was done about 45min after ridding so warm but by no means hot. The engine runs with no misfires or stumbling since i installed the new shims but there is a significant loss in power, specifically torque. What am I overlooking or have yet to investigate?

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Before we go further....did you re-check the cam timing?
Also...you know you have a decent seal on the rear cylinder. Put the air line on that cylinder and listen for noise through the cases as a comparison. You will be down on power from a gasket and you did note that you have lost coolant.

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Hi Friends,
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